Reconstructed historical temperature and flood/drought variations based on historical records for the Yangtze Delta are analyzed with the help of power spectral and continuous wavelet analyses. Three distinct climate periods can be identified in the Yangtze Delta: Warm Medieval Period (AD 1000–1400), Little Ice Age (AD 1400–1920), and the ongoing well-established Global Warming Period (AD 1920–present). The variability of temperature is of great magnitude, and periods dominated by warm/cold temperature are usually interrupted by cold/warm periods. A comparison of flood/drought variations and temperature variations indicates that there are obviously no fixed modes of climate changes such as warm-wet, cold-wet, warm-dry or cold-dry. However, the results demonstrate that large-magnitude temperature variations usually lead to a higher frequency of flood/drought hazards in the Yangtze Delta. Furthermore, the frequency of flood/drought events usually increased in the transition periods from one climate state to another. The ongoing period of climate change is another transition from cold temperatures during the Little Ice Age to increasing temperatures and variability. This might increase the probability and reoccurrence of flood/drought events and other extreme climate events in the Yangtze Delta.